The proposed research follows up during early adulthood, and already identified and well characterized onset-cohort of insulin dependent diabetic (IDDM) patients (N=61), together with a comparison sample of age matched patients identified at the time of an acute medical illness (N=62). These patient samples, first evaluated in childhood and early adolescence (ages 9-16), have been followed over a seven-year period, using a repeated measures design. We have assessed: 1) family dimensions including interactions, coping strategies, and environments; 2) individual patient psychosocial functioning including behavior problems, self-esteem, and ego development; and 3) in the diabetic sample, glycemic control, adherence, adjustment to diabetes, and early signs of microvascular complications. In this follow up, a single panel of observations will assess the social development of these patient samples during young adulthood (ages 20-27), eleven years after diagnosis. This panel includes assessment of patients' familial attachments, close peer relationships, and social competence. By evaluating these aspects of relationships, we will be focussing on dimensions which have been found previously to be important predictors of health outcomes, and which are developmentally the most meaningful indicators of early adult psychosocial functioning. We will also evaluate diabetes-specific outcomes including: diabetes adjustment, metabolic control, microvascular complications, and adherence. Three principal research questions will be addressed: 1) How do diabetic and non-diabetic young adults differ in their social development as measured through assessment of peer relationships and family attachments? 2) Do family measures such as cohesion and conflict gathered during childhood and adolescence predict diabetes-specific functioning (e.g. metabolic control and adherence) in young adult years? 3) Do individual measures such as adjustment predict diabetes-specific functioning in young adult years? Data analyses for these questions will utilize univariate and multivariate techniques. By following these samples of patients into their young adult years, we will have for the first time traced--sequentially and prospectively--a group of diabetic children and adolescents to an era in which they will be making the transition to a more independent functioning.